I don't receive the error message I'm supposed to

My textbook says "there must always be the same number of values in each row and each column of a matrix"

They give this as an example of proper code:

>>mat=[431;256]

mat=
    4 3 1
    2 5 6

And this as an example of improper code:

    >>mat=[357;12] 

It says I should be getting an error that says "dimensions of arrays being concatenated are not consistent", but I don't get this error, instead MATLAB registers the code as:

mat=

123

12

Does anyone know what goes on here? Thanks in advance!

[Walter Roberson]

Somehow you are missing spaces.

>> mat=[431;256]

mat =

   431
   256

>> mat=[4 3 1;2 5 6]

mat =

     4     3     1
     2     5     6

Answer 1

[Kavin Kadam]

It is because there is no space between 123 and 12, so it interprets it as 1 number.

Answer 2

[Image Analyst]

That code is perfectly fine. Perhaps the bad code is

mat=[3,5,7;1,2] % Preferred - commas between

or

mat = [3 5 7; 1 2] % Not preferred - spaced between  Might get orange warning squiggles.

In those cases there would be 3 columns in the first row and 2 columns in the second row, which is not allowed.